An exclusive conveying tool has been used in the past on a heat treatment process of the semiconductor wafer or on the conveying line thereof in the semiconductor manufacturing process, in order to transfer and/or convey a plurality of semiconductor wafers.
There are different cases about a size of an individual semiconductor wafer to be conveyed. Accordingly, in order to omit a step of changing the conveying tool for each time when the size of the semiconductor wafer to be conveyed is changed, a conveying tool that can cope with the conveyance of the wafers with plural sizes by one species of the conveying tool has been known (see Patent Documents 1 and 2).
In the Patent Document 1, a wafer fork has been disclosed in which holding pins are fixed into their corresponding fixing holes according to a magnitude of a diameter of the semiconductor wafer to be conveyed so as to be able to cope with the conveyance of the wafers with plural sizes. Further, in the Patent Document 2, a wafer-holding table that can cope with the conveyance of the wafers with plural sizes has been disclosed. According to this wafer-holding table, a semiconductor wafer W is conveyed by conveying beams which move vertically and horizontally by a vertical cylinder and a horizontal cylinder. This is so-called “a wafer-holding table of walking beam system”. In connection therewith, there are at least three species of heights in the pins for supporting the wafer; the pins each having the same height, are arranged around the same circumference; and the respective pins are concentrically arranged so that the outer ones become taller in an order of heights thereof. It is configured that the wafer supported by the pins each having a height corresponding to a dimension of the wafer is positioned by contacting it with next higher pins.
As another example of the wafer conveyance in which it is possible to cope with the conveyance of the wafers with plural sizes, the example as shown in FIG. 5 is illustrated. In a wafer conveying tool 200 shown in FIG. 5, a base plate 10 and conveying guides 11 are tightened by bolts 14 and the like. An opening 15 having an outer diameter that is smaller than a diameter of a wafer W3 (or W4) is present at a center of the base plate 10. Pins 16A through 16C and 18A through 18C for supporting the wafer W3 (or W4) from below and guides 17A through 17C and 19A through 19C for preventing misalignment of the wafer W3 (or W4) are concentrically arranged on the base plate 10. Three guides 17A through 17C and three 19A through 19C are respectively provided for the wafer W3 (and W4) and the wafer conveying tool 200 conveyed by a conveying device, not shown, along an arrow direction.